1. Field of the Invention
This invention relates to a method of sizing a cheese.
2. Description of Related Art
A cheese is obtained by winding a fiber, for example, cotton or blended yarns comprising cotton and polyester around a porous cylindrical core made of, for example, a synthetic resin in such a manner as to give a thickness of, for example, from 7 to 8 cm.
The sizing of the cheese is usually effected by introducing the cheese into a size tank and forcing a size in the tank to circulate from the internal layer of the cheese to the external layer thereof via the intermediate layer, or vice versa, through the core of the cheese.
Examples of the sizing agent to be used for sizing a cheese include those which are in the form of an aqueous solution of a polymer such as grafted starch (refer to Japanese Patent Laid-Open No. 33279/1989), etherified starch (refer to Japanese Patent Laid-Open No. 180683/1983), and a polymer compound having an average molecular weight of 20,000 or more which comprises a polyhydroxy compound having an average molecular weight of 1,000 or more as the main component (refer to Japanese Patent Laid-Open No. 9275/1984).
However these sizing agents of the aqueous polymer solution type have each some disadvantages such that it shows a poor adsorption efficiency and thus the sizing agent remains in the residue and that it requires a relatively high temperature (i.e., 80.degree. to 90.degree. C.) for gelatinization.
On the other hand, the use of a cationic emulsion polymer as a sizing agent enables the selective adsorption on a fiber, which serves to considerably save the amount of the sizing agent to be used.
However it is very difficult to make a cheese, which is a highly dense fiber aggregate, homogeneously adsorb a cationic emulsion polymer without giving any difference in the density among the internal, intermediate and external layers.
More specifically, a cheese is usually dyed at a temperature as high as 90.degree. to 130.degree. C. and then an unfixed dye is removed by soaping or reductive washing, followed by washing with hot or cold water. Since the sizing is conducted thereafter, the solution temperature in the sizing will never be lower than 30.degree. C. When a cationic emulsion polymer is used as a sizing agent, therefore, it will undergo completely heterogeneous adsorption. Namely, the forced circulation of the size in the cheese from the internal layer to the external layer via the intermediate layer will cause the internal layer to adsorb most of the size. As a result, no size will adhere to the intermediate and external layers.
Although low temperature sizing methods have been proposed in order to solve the above-mentioned problems (refer to Japanese Patent Publication No. 61705/1987 and No. 12195/1988), they are seriously restricted from the industrial viewpoint for the reasons described above.